Spatiotemporal Variation and Potential Drivers of Macroplastic Pollution Across Urban Riparian Corridors in...

Macroplastics are a major contributor to plastic pollution in riverine environments, however, the spatiotemporal scales over which plastic accumulation and remobilization occur remain poorly understood, limiting the interpretation of riverine macroplastic patterns. Here, we present the first dataset on macroplastic debris collected from Patagonian riparian corridors across different seasonal periods. Field surveys were conducted during 2022 and 2023 across ten fluvial systems: six urban streams, analyzed at the reach level (upstream, urban, and downstream), and four minimally disturbed sites categorized as reference streams. Macroplastic items were recorded in all reaches of the urban streams as well as at the reference sites. The highest macroplastic densities occurred in urban reaches during spring, with single-use plastics dominating, consisting mainly of plastic bags and, to a lesser extent, food wrappers. Macroplastic accumulation in riparian corridors was primarily associated with the degree of urbanization and the proportion of impervious areas present. Meteorological factors such as precipitation, air temperature, and wind speed showed no direct influence, at least in the seasonal analysis. Identifying spatial and temporal hotspots of macroplastic accumulation in Patagonian riparian corridors is crucial. The persistence of these macroplastics alters the structure and aesthetic quality of habitats, and can also accelerate biodiversity loss as well as the downstream transport of plastic waste, generating a continuous supply of secondary microplastics in freshwater environments. These insights are essential for improving the monitoring of pollution sources, facilitating future management actions, and promoting their eventual removal from Patagonian stream systems.